1. Field of the Invention
The present invention relates to a mount apparatus and, more particularly, to a mount apparatus used in manufacturing a semiconductor device.
2. Description of the Related Art
Conventionally, non-defect/defect determination of an adhesive layer for adhering a semiconductor chip to a mount substrate (e.g., a bed of a lead frame) is performed as follows. That is, a product is picked from a mount apparatus upon completion of a mounting operation, and sampling inspection of the product is performed on an off-line state.
The thickness of each adhesive layer is calculated as follows. That is, the difference between the upper surface of a chip and the upper surface of a mount substrate is measured using a micrometer, and the thickness of the chip itself is subtracted from the difference.
FIG. 1A is a sectional view for explaining a method of measuring the thickness of an adhesive layer, and FIG. 1B is a plan view for explaining a method of measuring a degree of spread of the adhesive layer.
Referring to FIG. 1A, reference numeral 1 denotes a semiconductor chip, and the chip 1 is fixed on a substrate 3 with an adhesive layer 2 consisting of an adhesive. As shown in FIG. 1A, a difference t between the upper surface of the chip 1 and the upper surface of the mount substrate 3 is measured by the above method, and the known thickness tc of the chip 1 is subtracted from the difference t, thereby obtaining a thickness tm of the adhesive layer 2.
The degree of spread of the adhesive layer 2 can be estimated such that an adhesive amount squeezed out of the chip 1 is observed using a microscope.
As shown in FIG. 1B, when the degree of squeeze-out of the adhesive squeezed out of the chip 1 on the mount substrate 3 is observed, it is estimated that the adhesive layer 2 spreads over a region 4 indicated by a hatched region.
In this manner, non-defect/defect determination of the adhesive layer is performed by a cumbersome manual operation in an off-line state in which a product is picked from the mount apparatus.
The non-defect/defect of the adhesive layer considerably depends on the states (viscosity, dropping amount, droplet shape, and the like) of an adhesive dropped on the mount substrate immediately before a mounting operation, and many defects may be continuously formed on a manufacturing line.
However, although mounting operations are sequentially performed by the mounting apparatus, the non-defect/defect of an adhesive layer can be checked only sometimes by sampling inspection. For this reason, when a defect is detected, a large number of defects have already been frequently formed.
In the sampling inspection, since the non-defects/defects of the adhesive layers of all products cannot be checked, defective products flow into the next process, so that troubles may be caused later.
As described above, since there is no technique of performing non-defect/defect determination of an adhesive layer immediately after a mounting operation to detect a defective product in real time, defective products are continuously formed, and the defective products flow into the next process line, thereby causing troubles. More particularly, the former decreases a production yield, and the latter cannot help stopping the production line, thereby decreasing a throughput.